Study of seed dispersal by Emu (Dromaius novaehollandiae) in the Jarrah (Eucalyptus marginata) forests of south-western Australia through satellite telemetry

Global positioning system (GPS) technology for tracking wildlife continues to evolve at a remarkable pace. As animal movement is increasingly recognised as being critical for several ecological processes, advanced telemetry technology permits collection of a high volume of data across short time intervals that was previously unobtainable. Here we describe the use of GPS telemetry to track the movements of five tagged Emus (Dromaius novaehollandiae Latham) released within the Jarrah (Eucalyptus marginata Sm.) forests of south-western Australia. The Emu plays a significant role as a seed disperser for many species. Describing the movement patterns of this species is a key requirement in refining the extent and significance of its contribution to seed dispersal, both locally and over long distances. We found that Emus followed a typical correlated random walk pattern and that each bird demonstrated a variable response to the landscape in terms of behaviour, extent of movement and habitat selection. From a methodological perspective, 50% of our devices detached before 30 days of GPS locations could be collected, reflecting a need for device refinement for future studies on large ratites. Nevertheless, our preliminary data provide useful insights into the movements of the Emu and potential impacts on seed dispersal within the Jarrah forests

Ecology of fire-tolerant podocarps in temperate Australian forests

Podocarpus drouynianus and P. spinulosus are two unusual conifers restricted to southwestern and eastern Australia, respectively. The species are morphologically similar and genetically closely related to each other but rather distant from other members of the subgenus Foliolatus. Both species have retained ancestral podocarp characteristics such as dioecy, wind pollination, and large, animal-dispersed seeds with recalcitrant germination. They also thrive on soils with generally low nutrient content. However, they have several innovations that ensure their success in an environment that would generally be considered unsuitable for podocarps. Both species have much higher leaf length to width ratios than other Podocarpus species: this presumably aids their survival on low-to moderate-rainfall sites. They both resprout strongly after fires, and at least for P. drouynianus, seed production is cued by defoliation, and sporophylls are produced most prolifically on new growth one year after fire. The species are unique in the genus as being successfully adapted to a relatively dry, fire-prone environment

A variable sense of place as exemplified in an iconic urban reserve in Western Australia

The 'sense of place' that a city and its inhabitants come to identify themselves by can have profound impacts on the way that urban landscapes develop. In the case of Perth, its icons are the Swan River, The sandy beaches of the Indian Ocean coastline, and Kings Park. While the first two have defined the way that the city is laid out and has grown, the latter has fostered the development of an Australian garden and landscape approach to urban design, and a strong native species conservation ethic

Fire-stimulated reproduction in the resprouting, non-serotinous conifer Podocarpus drouynianus (Podocarpaceae): the impact of a changing fire regime

Species with fire stimulated reproduction (fsr) are common in Mediterranean climate ecosystems. We investigated how season of, and time since, fire affects seed production in Podocarpus drouynianus F. Muell., a dioecious resprouting coniferous shrub endemic to the jarrah (Eucalyptus marginata Sm.) forests of southwestern Australia, and if the now largely managed fire regime in these forests poses a risk to its persistence. We hypothesised that, like other species showing fsr, seed production in P. drouynianus would be limited to the first few years following fire and seed set would be lower after spring burns. Mature plants regenerated rapidly from buried stem tissue (lignotuber) after fire, producing abundant sporophylls in autumn 12–18 months later. Stands burnt in autumn showed peak seed production 1 year later, while for those burned in spring, peak seed production was delayed until the second autumn after fire. Limited seed production occurred for up to 3 years following fire, but no seed production was observed in longer unburnt (>10 years since fire) stands. While we did not observe a significant impact of fire season on seed production, seed weight and viability were lower for spring-burnt plants. Population-level effects associated with plant density may also have negative impacts on P. drouynianus demography, with females within a small population burnt in autumn producing very few seeds 12 months following fire. Interactions between climate change, fire regimes and fire management practices need to be considered in order to best safeguard the long-term persistence of this conifer species

Fire regime and climate determine spatial variation in level of serotiny and population structure in a fire-killed conifer

Fire-killed serotinous trees are often dominant species in fire-prone regions with contrasting wet and dry seasons. We studied a serotinous fire-killed conifer (Callitris preissii, Cupressaceae) to identify the influence of fire regime and climate on geographic variation in level of serotiny, recruitment and population structure. We measured population size distributions, seedling recruitment and level of serotiny for sample stands across a climatic gradient from mesic coastal (including two islands) to semi-arid inland sites in SW Australia. Trees on islands were mostly non-serotinous and were only weakly serotinous on the adjacent mainland in the higher rainfall West coast region. In the semi-arid Goldfields and South inland, and the higher rainfall South coast region, trees were more strongly serotinous with up to six cohorts of closed cones retained on trees. Level of serotiny was stronger at the drier end of the climatic gradient where severe to extreme fire danger weather occurs most frequently, and where vegetation type (e.g., shrublands) supports frequent crown-type, stand-replacing fires. Recruitment was most abundant post-fire in all regions, but seedlings also established inter-fire where there was regular seed fall due to low level of serotiny or spontaneous release of seeds from old cones on trees with a high cone load. Population structures for mainland stands shifted from approximately reverse-J (indicating continuous recruitment) in mesic regions to mainly unimodal (establishment mostly after fire) in drier, inland regions, although some long-unburned inland stands showed occasional inter-fire recruitment, likely linked to high rainfall years. Unimodal population structures characterized islands, where previous studies have identified herbivory on seedlings by refugial populations of native macropods as a limiting factor on inter-fire establishment. Understanding landscape context, response to disturbance, biotic interactions and reproductive traits of dominant species is essential in conservation planning in a rapidly changing global environment

Detecting plant spatial pattern change after disperser loss: A simulation and a case study

Disruption of seed dispersal processes may affect plant population spatial structure. We used a spatial simulation model and an empirical case study to assess the conditions under which the loss of seed dispersers has a detectable effect on a species' spatial pattern. Our simulation experiments suggested that detecting spatial change following disperser loss will be difficult, except when rates of fruit removal are initially high and then completely disappear. To contextualize the simulation modeling, we used spatial point pattern analyses to characterize the spatial pattern of two large‐seeded species (Leucopogon nutans, a fire‐killed seeder shrub and Macrozamia riedlei, a long‐lived, resprouting cycad) in the jarrah (Eucalyptus marginata) forests of southwestern Australia. The plant species' primary disperser, the emu (Dromaius novaehollandiae), was absent from one of the sites we considered, but present at the other two. There was no detectable difference for either plant species in the strength of aggregation between sites with and without emu. However, even if disperser loss may not greatly affect local spatial structure for most plant species, it is likely to be important for long distance dispersal and genetic structuring of populations, so accurate characterization of the dispersal kernel is critical, especially in terms of plant emigration

Variation of Serotiny in Callitris preissii related to fire and climate in Western Australia

Delayed seed release (serotiny) is a syndrome of adaptive significance in a randomly fluctuating environments such as fire-prone and arid ecosystems. Selective forces involving fire, rainfall and seed predators have been suggested as factors influencing serotiny. Callitris preissii is a conifer in the Cupressaceae found only in Australia and New Caledonia and it is regarded as “fire sensitive”. It has excellent potential for erosion control of sandy, alkaline coastal sites and has been used in revegetation in many region in Western Australia. We compared the degree of serotiny among different populations and related this to fire history, climate and seedling predators.The relative ages of cohorts of closed cones were determined on trees in populations ranging from arid interior sites to islands with much higher annual rainfall. The individuals with the greatest serotiny grow at inland sites (Kalgoorlie and Lake Grace), while the plants with the lowest serotiny were recorded at island sites. Seedling recruitment after fire at Boorabin National Park burnt in 2007 was dense and at Cape Le Grand National Park near the south coast of Western Australia a patchy fire produced many seedlings in burnt areas. However in both areas seedlings were absent from unburnt sections. The strong serotiny at these sites ensures an abundant seed rain after fire kills adult plants. The weaker serotiny at the island sites might be thought to relate to the possibility that there is interfire recruitment of the plants

Offset or off-the-mark? Seedling emergence and survival following topsoil transfer in Banksia woodland

Floristically rich and ecologically complex, Mediterranean-type ecosystems are rapidly being cleared for urban, horticultural and industrial development. A prime example is Banksia woodland, an ecosystem restricted to the Swan Coastal Plain in Western Australia. In order to compensate for the clearing of Banksia woodland due to urbanization, land developers are required to attempt biodiversity offsets whereby topsoil from newly cleared landscapes can be moved to degraded land with the aim of restoring Banksia woodland. Yet the science and practice of restoration ecology is not sufficiently advanced to know for certain that this aim can be achieved. Assessing the efficacy of a spectrum of restoration techniques will provide new insights for the restoration of endangered plant communities, and critically, a test of the feasibility of biodiversity off setting. The topsoil was subjected to three site-scale treatments: altering topsoil depth, ripping & herbivore exclosures. Additionally, six plot-scale treatments were applied to explore germination effect (three smoke water-related, topsoil heating) and competition effect (herbicide & artificial shade installation) on native seedlings’ emergence and survival. Significantly fewer seedlings emerged from ripped (17.01 ±1.03 SE) than unripped plots (37.99 ±2.05 SE). Species richness was similar across all treatments with a total number of native plant species emerging from the transferred topsoil of 129 in the first year and 115 in the second year. Mean survival rates of native perennial seedlings were very low (year I = 11.1% & year II = 1.2%). The maximum average survival was recorded under artificial shade (41% ±12.2 SE)

National regulation and the changing geography of the Irish dairy processing industry

SIGLEAvailable from British Library Document Supply Centre-DSC:0738.95405(16) / BLDSC - British Library Document Supply CentreGBUnited Kingdo